The objective of this research is to isolate the major antigens of Legionella pneumophila. A high molecular weight antigenic component of L. pneumophila has been isolated from the Philadelpha and Togus isolates (serotypes 1 and 2, respectively). Preliminary evidence indicates that this antigen is predominantly carbohyrate and is responsible for type specificity. Part of this research proposal is designed to continue our studies on this antigen and to isolate and purify similar type specific antigens from the Bloomington 2 and LA isolates (serotypes 3 and 4 respectively). The development of an ELISA assay for purified type-specific L. pneumophila antigens will be investigated. The significance of the type specific antigen in protection studies in guinea pigs will also be studied. A second major antigen associated with the Philadelphia isolate has recently been identified. This antigen appears to be a protein. Studies will be initiated to isolate this antigen from the 4 serotypes and to immunochemically and biochemically characterize its properties. Studies are included on the isolation of endotoxin to answer the currently unresolved question as to whether L. pneumophila contains classical lipopolysaccharide similar to that found in other gram negative bacteria. The possible role of endotoxin as a major antigen of L. pneumophila will also be investigated.